Chances are that you probably aren't going to be able to hold a ton...Last I remember, I barely fit all of the Otaku Dream mixes on a 4gb memory key, though I don't remember if they had the videos or not. I guess if you have 10+ games, they are probably taking maybe a good 600-700mb, if not more...and a sm song is maybe around 5mb(?) so you would be able to fit maybe 280+ songs disregarding all other forms of data that you might have on your mSD...The best way to optimize your space would be to tediously go through every folder and delete all of the unneeded stuff (meaning that each folder would have a song and an .sm file I believe)...but that sounds seriously bothersome to do for 280+ songs...